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3 If desired, handle caret events by registering a CaretListener for the text field Caret events are generated each time the caret (also commonly referred to as the cursor) changes position 4 To obtain the text currently displayed in the text field, call getText( ) 5 You can set the text by calling setText( ) You can use this method to reset the text, for example, if the user makes a mistake 6 You can obtain text that has been selected by calling getSelectedText( ) 7 You can cut selected text by calling cut( ) This method removes the text and also puts the cut text into the clipboard You can copy selected text, but not remove it, by calling copy( ) 8 You can copy whatever text is in the clipboard into the text field at the current caret location by calling paste( )

JTextField inherits the abstract class javaxswingtextJTextComponent, which is the superclass of all text components JTextComponent defines the functionality common to all of the text components, including JTextField For example, the cut( ), copy( ), and paste( ) methods are defined by JTextComponent The model for JTextField (and all other text components) is javaxswingtextDocument JTextField defines several constructors The two used here are: JTextField(int cols) JTextField(int str, int cols) Here, cols specifies the width of the text field in columns It is important to understand that you can enter a string that is longer than the number of columns It s just that the physical size of the text field on the screen will be cols columns wide The second constructor lets you initialize the text field with the string passed in str Pressing ENTER when a text field has focus causes an ActionEvent to be generated If you want to handle this event, you must register an ActionListener for the text field The ActionListener interface defines only one method, actionPerformed( ) This method is called whenever an action event is generated by the text field For details on handling action events, see Create a Simple Push Button A JTextField has an action command string associated with it By default, the action command is the current contents of the text field Thus, the action command string changes each time the contents of the text field change Although this may be useful in some situations, it makes it impossible to use the action command string as a means of determining the source of an action event If you do want to use the action command string to identify a text field, then you must set the action command to a fixed value of your own choosing by calling the setActionCommand( ) method, shown here void setActionCommand(String newCmd) The string passed in newCmd becomes the new action command The text in the text field is unaffected Once you set the action command string, it remains the same no matter what is entered into the text field

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Each a time a text field s caret changes location, such as when you type a character, a CaretEvent is generated You can listen for these events by implementing a CaretListener By handling caret events, your program can respond to changes in the text field as they occur, without waiting for the user to press ENTER CaretListener is packaged in javaxswingevent It defines only one method, called caretUpdate( ), which is shown here: void caretUpdate(CaretEvent ce) Remember, a caret event is generated each time the caret changes position This includes changes to the caret caused by selected text, cutting or pasting, or repositioning the caret within the text Therefore, handling caret events lets you monitor changes to the text in real time To obtain the string that is currently displayed in the text field, call getText( ) on the JTextField instance It is declared as shown here: String getText( ) You can set the text in a JTextField by calling setText( ), shown next: void setText(String text) Here, text is the string that will be put into the text field A subset of the characters within a text field can be selected, either by the user or under program control You can obtain the portion of the text that has been selected by calling getSelectedText( ), shown here: String getSelectedText( ) If no text has been selected, then null is returned Although the precise procedures may differ in different environments, JTextField automatically supports the standard cut, copy, and paste editing commands that let you move text between a text field and the clipboard (For example, in Windows you can use CTRL-X to cut, CTRL-V to paste, and CTRL-C to copy) You can also accomplish these actions under program control by using the methods cut( ), copy( ), and paste( ), shown here: void cut( ) void copy( ) void paste( ) The cut( ) method removes any text that is selected within the text field and copies it to the clipboard The copy( ) method copies, but does not remove, the selected text The paste( ) method copies any text that may be in the clipboard to the text field If the text field has selected text, then that text is replaced by what is in the clipboard Otherwise, the clipboard text is inserted immediately before the current caret position